A, the captain of a steam vessel, suddenly and without any fault or negligence on his part, finds himself in such a position that before he can stop his vessel, he must inevitably run down a boat B, with twenty to thirty passengers on board, unless he changes the course of his vessel, and that by changing his course, he must incur risk of running down a boat C with only two passengers on board, which he may possibly clear. Here if A alters his course without any intention to run down the boat C and in good faith for the purpose of avoiding the danger to the passengers in boat B. But in the course of this action A runs down boat C.